The present invention relates to a filter element for separating a liquid, particularly an air deoiling element, having a drainage tube through which the separated liquid can be removed.
The invention also relates to a drainage device that contains such a drainage tube and to a filter apparatus provided with such a drainage tube.
Filter elements with drainage tubes are available in the prior art. They are used, for example, to de-oil compressed air in compressed air systems supplied by an oil-lubricated compressor. Another possible application for such filter elements is the de-oiling of crankcase gases from an internal combustion engine.
In annular filter elements in which the gas flows from the inside radially outwardly toward the outside, liquid separated from the gas collects in the interior of the preferably cylindrical filter cartridge. From there it is withdrawn by suction through a drainage tube, which extends into the interior of the filter cartridge. This drainage tube may be an integral component of the upper end disk of the filter element, so that it is possible to fix it in the position necessary for separated oil to be withdrawn by suction. However, the manufacture of a filter element with firmly mounted drainage tube is complicated, so that the filter element is not economical.